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A fast low-power optical memory based on coupled micro-ring lasers


The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information1. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data2. Recently, ring lasers with extremely small size and low operating power have been made3,4,5,6,7, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40 µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20 ps with 5.5 fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

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Figure 1: Two micro-ring lasers coupled via a waveguide.
Figure 2: A memory element formed by two 16 µm diameter micro-ring lasers coupled via a waveguide on a InP/InGaAsP photonic integrated circuit.
Figure 3: Oscilloscope traces showing the switching of the memory element between states.


  1. Cotter, D. et al. Nonlinear optics for high speed digital information processing. Science 286, 1523–1528 (1999)

    Article  CAS  Google Scholar 

  2. Zimmerman, S., Wixforth, A., Kotthaus, J. P., Wegscheider, W. & Bichler, M. A semiconductor-based photonic memory cell. Science 283, 1292–1295 (1999)

    Article  ADS  Google Scholar 

  3. Fujita, M., Ushigome, R. & Baba, T. Continuous wave lasing in GaInAsP microdisk injection laser with threshold current of 40µA. Electron. Lett. 36, 790–791 (2000)

    Article  CAS  Google Scholar 

  4. Spillane, S. M., Kippenberg, T. J. & Vahala, K. J. Ultralow-threshold Raman laser using a spherical dielectric microcavity. Nature 415, 621–623 (2002)

    Article  ADS  CAS  Google Scholar 

  5. Polman, A., Min, B., Kalkman, J., Kippenberg, T. J. & Vahala, K. J. Ultralow-threshold erbium-implanted toroidal microlaser on silicon. Appl. Phys. Lett. 84, 1037–1039 (2004)

    Article  ADS  CAS  Google Scholar 

  6. Levi, A. F. J., McCall, S. L., Pearton, S. J. & Logan, R. A. Room temperature operation of submicrometre radius disk laser. Electron. Lett. 29, 1666–1667 (1993)

    Article  CAS  Google Scholar 

  7. Baba, T. & Sano, D. Low-threshold lasing and Purcell effect in microdisk lasers at room temperature. IEEE J. Select. Top. Quant. Electron. 9, 1340–1346 (2003)

    Article  ADS  CAS  Google Scholar 

  8. Van, V. et al. Optical signal processing using nonlinear semiconductor microring resonators. IEEE J. Select. Top. Quant. Electron. 8, 705–713 (2002)

    Article  ADS  CAS  Google Scholar 

  9. Yanik, M. F., Fan, S. & Soljacic, M. High-contrast all-optical bistable switching in photonic crystal microcavities. Appl. Phys. Lett. 83, 2739–2741 (2003)

    Article  ADS  CAS  Google Scholar 

  10. Keyes, R. W. Fundamental limits of silicon technology. Proc. IEEE 89, 227–239 (2001)

    Article  CAS  Google Scholar 

  11. Kawaguchi, H. Bistabilities and Nonlinearities in Laser Diodes (Artech House, Boston, 1994)

    Google Scholar 

  12. Buczek, C. J., Freiberg, R. J. & Skolnick, M. L. CO2 regenerative ring power amplifiers. J. Appl. Phys. 42, 3133–3137 (1971)

    Article  ADS  CAS  Google Scholar 

  13. Harder, C., Vahala, K. & Yariv, A. Measurement of the linewidth enhancement factor α of semiconductor lasers. Appl. Phys. Lett. 40, 328–330 (1983)

    Article  ADS  Google Scholar 

  14. Sakai, A. & Baba, T. FDTD simulation of photonic devices and circuits based on fan-shaped microdisks. J. Lightwave Technol. 17, 1493–1499 (1999)

    Article  ADS  Google Scholar 

  15. Hagness, S. C., Rafizadeh, D., Ho, S. T. & Taflove, A. FDTD microcavity simulations: design and experimental realization of waveguide-coupled single-mode ring and whispering-gallery-mode disk resonators. J. Lightwave Technol. 15, 2154–2164 (1997)

    Article  ADS  CAS  Google Scholar 

  16. Noda, S., Chutinan, A. & Imada, M. Trapping and emission of photons by a single defect in a photonic bandgap structure. Nature 407, 608–610 (2000)

    Article  ADS  CAS  Google Scholar 

  17. den Besten, J. H. et al. A compact digitally tunable seven-channel ring laser. IEEE Photon. Technol. Lett. 14, 753–755 (2002)

    Article  ADS  Google Scholar 

  18. Smith, S. D., Walker, A. C., Tooley, F. A. P. & Wherrett, B. S. The demonstration of restoring digital optical logic. Nature 325, 27–31 (1987)

    Article  ADS  Google Scholar 

  19. Ledentsov, N. N. et al. Quantum-dot heterostructure lasers. IEEE J. Select. Top. Quant. Electron. 6, 439–451 (2000)

    Article  ADS  CAS  Google Scholar 

  20. Chuang, S. L. Physics of Optoelectronic Devices (Wiley-Interscience, New York, 1995)

    Google Scholar 

  21. Painter, O. et al. Two-dimensional photonic band-gap defect mode laser. Science 284, 1819–1821 (1999)

    Article  CAS  Google Scholar 

  22. Ryu, H.-Y. et al. Square-lattice photonic band-gap single-cell laser operating in the lowest-order whispering gallery mode. Appl. Phys. Lett. 80, 3883–3885 (2002)

    Article  ADS  CAS  Google Scholar 

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This work was supported by the Netherlands Organization for Scientific Research (NWO) through the ‘NRC photonics’ grant.

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Correspondence to Martin T. Hill.

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Hill, M., Dorren, H., de Vries, T. et al. A fast low-power optical memory based on coupled micro-ring lasers. Nature 432, 206–209 (2004).

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